Hydraulic turbine



June 4, 1929. MOODY I 1,716,078

' HYDRAULIC TURBINE Original Filed June 25. 920

Z jNVENTOR By ZZZ/@441 gw/m Patented June 4, 1929.

UNIT sarss LEWIS FERRY MOODY, OF PHILADELPHIA, PENNSYLVANIA.

HYDRAULIC TURBINE.

Original application filed June 25, 1920, Serial No. 391,583.

This invention relates to hydraulic turbines, and particularly toturbines of high specific speed through which large quantities of waterflow at high velocity head compared to the net head on the plant, and toturbines having wicket gate or movable guide-vane means for regulatingthe flow.

The object of the invention is to provide a turbine installation inwhich large quantities of water can be handled within a limited space,and within which the water can be set into motion at high velocity andagain retarded to a low velocity at discharge with minimum loss of head,and may impart to the turbine runner a high velocity of rotation; and itis at the same time an object of the invention to provide such a turbinewith an operating mechanism for controlling the power and speed, soarranged that the working parts are readily accessible outside of thewater passages while the turbine is in opera tion.

Another object of the invention is to provide a turbine in which theintake and out flow passages and the control means are adapted toproduce a whirling body of water within which the runner rotates at highspeed, and to decelerate the velocity of whirl in a draft tube spreadingoutward away from the turbine axis on all sides so as efficiently toregain the kinetic energy of the water leaving the runner.

The turbine to which the specific features of this invention areparticularly adapted is one having a propeller type runner, that is, anunshrouded axial flow runner having a small number-of vanes. In order toenable such a runner to operate at high velocity the draft tube of theturbine of this invention expands radially at its discharge end to adiameter considerably greater than that of the runner, so that the watermay leave the runner with a considerable velocity of whirl,

. this whirl being efliciently decelerated and the water leaving thedischarge end of the draft tube at low velocity.

Further objects of the invention particularly in the arrangement of theturbine units and passages in the power house will appear from thefollowing description taken in connection with the accompanying drawingsin which:

Fig. 1 is a vertical sectional view of a turbine installation taken online 1-1 of Fig. 2 showing one embodiment of the invention;

Divided. and this application filed March 29,

Serial N 0. 98,083.

Fig. 2 is a horizontal sectional view on line 22 of Fig.1; and

Fig. 3 is a vertical sectional view illustrating a modified form of adraft tube.

In the embodiment of the invention illustrated a turbine with a verticalshaft 10 has a'runner 11 in a water passage W. The intake passage 12leading to this water passage is a contracting volute having inner walls13 and 1d substantially circular and converging to the entrance space 15of the passage 'W. In this entrance space 15 are the adjustable guidevanes or wicket gates 16 controlled through their stems 17 by theoperating means 18 around shaft 10.

The flow enters in through the intake passage 12 with a whirl and passesthrough adjustable guide vanes 16 in a radial direction and with a whirland is turned downward toward the axial direction in the water passagel/V. In an intermediate position in this water passage WV the blades 20of the runner 11 are interposed, extending diagonally across the flowand being of the diagonal inward flow type. This runner rotates at highspeed under light torque and the discharge from it has a considerablevelocity of whirl the energy of which would be largely lost in theordinary straight draft tubes adapted to regain only the axialcomponents of the discharge.

This invention is not restricted to any particular angles of the runnerblades, but is applicable even when the blades are normal to the axisand the runner is of the axial flow type.

The drafttube D from water passage W spreads or expands radially in thedirection of flow so as to permit the whirling discharge to bedecelerated on expanding spiral lines and at the same time the area ofthe draft tube across the meridian components of flow graduallyincreases. This provides for a natural gradual deceleration of both theaxial and the whirl components of flow so as to regain the energy ofboth by reconverting it into effective pressure head. It should beunderstood that as the Water recedes fromthe axis, since its moment ofmomentum will re main the same its velocity of whirl will vary inverselyas the distance from the axis. The spreading draft tube D thus lowersthe velocity of the discharge and delivers it to the outflow passage Cof volute form expanding in the direction outflow to continue theconversion of velocity into pressure head. The deceleration of thedischarge requires constantly widening passages and to provide anoutflow passage of large cross section without exceeding the allowableover-all dimensions, as determined for instance by the intake passage12, the outflow volute C is ex tended to an undercut- 22 below thecentral the following principle :It first diverts the water from theturbine axis in order to increase the radius of the paths of thewhirling flow, in a. space contained between two surfaces of revolutionin which the whirling flow can freely proceed. At the point of greatestradius (the magnitude of this radius being limited by the spacerestrictions of'the power house) the form 0t passage ceases to be aspace contained between surfaeeslof revolution, and from this pointonward the walls become spirals instead of circles about the axis, whenviewed in planes perpendicular to the axis. If in undercutting thecentral conical wall, to gain the required conduit area, the walls ofthe passage were continued surfaces of revolution approaching the axisonce more, the law of conservation of moment of momentum above referredto would cause the velocity of whirl again to increase, this velocityvarying inversely as the radius as already explained. By 'formingtheconduit walls as spirals, however, from the point of greatestradiusonward, the velocity is controlled at every point and made equal to thequantity flowing at each point divided by the transverse area of thechannel, which can be so gradually increased that the velocity willgradually and continuously decrease up to the point of lmal dischargeinto the tail race.

If still greater cross sectional area is desired for the outflowpassages the volute C may be extended upward as indicated at (Z in Fig.3 and still be kept within the permissible over-all dimensions. Theturbine installation above described provides entrance and dischargewater passages of large area with correspondingly low velocities andreonly a relatively small torque from the flow.

The relatively large quantities of water utilized'make it highlydesirable to have both with an entrance space having an inwardlydirected flow, of means for imparting a whirl to said flow, a curvingtransition space receiving the flow from-said entrance space and turningit toward the axial direction, a runner in said flow, a continuouslycurving draft tube receiving the flow fromsaid runner and turning itgradually toward the radially outvard direction in diverging spiral flowlines, a discharge passage receiving the outflow from said draft tubeand inwardly undercut under the spreading end of said draft tube.

2. In a hydraulic turbine the combination with an entrance spacehavingan inwardly directed flow, of means for-imparting a whirl tosaid-flow, a curving transition space re- 'ceiving the flow from saidentrance space and turning it toward the axial direction, a runner insaid flow, a continuously curving draft tube receiving the flow fromsaid runner and turning it gradually toward the radially outwarddirection in diverging spiral flow lines, a volute discharge passagereceiving the outflow from said draft tube and inwardly undercut underthe spreading end of said draft tube.

3. In a hydraulic turbine the combination with an entrance space havingan inwardly directed How, of means for imparting a whirl to said flow, acurving transition space receiving the flow from said entrance space andturning it' toward the axial direction, a runner in said flow, acontinuously curving draft tube receiving the flow from said runner andturning it gradually toward the radially outward direction in divergingspiral flow'lines, a discharge passage receiving the outflow from saiddraft tube inwardly undercut at its inner wall under the spreading endand uppercut above the outer wall of said draft tube.

fl. In a hydraulic turbine the combination with an entrance space havingan inwardly directed flow, of means for imparting a whirl to said flow,a curving transition spacersceiving the flow-from said entrance spaceand turning it toward the axial direction, a runner in saidfiow, acontinuously curving draft tube receiving the flow from said runner andturning it gradually toward the radially out i ward direction indiverging spiralflow lines,

a volute discharge passage receiving the outflow from said draft tubeinwardly undercut at its inner wall under the spreading end and uppercutabove the outer wall of said draft tube.

intake to said draft tube, a turbine runner in said conduit, a volutedischarge passage receiving the outflow from said draft tube andinwardly and spirally undercut under the spreading end of said drafttube.

6. In a hydraulic turbine the combination with an intake directed towardthe turbine axis and adapted to impart a whirl to the flow, ofadjustable guide vanes for varying said whirl, an outwardly directedoutlet adapted to discharge a whirling flow with a radial component awayfrom the turbine axis, a conduit leading from said intake to said outletcontinuously curving without sudden change in curvature, a turbinerunner in said conduit, and a volute discharge passage receiving theoutflow from said outlet and inwardly undercut under the spreading endof said outlet.

7. In a hydraulic turbine the combination with an intake adapted todirect the water radially inward and impart a whirl to the flow, ofadjustable guide vanes for varying said whirl, an outlet through whichtheflow passes outward with a whirl, a conduit curving in the samedirection and leading from said intake to said outlet, a turbine runnerin said conduit and spaced from said intake so as to leave a curvingtransition space between said intake and said runner, and a dischargepassage receiving the outflow from said outlet and inwardly undercutunder the spreading end of said outlet.

8. In a hydraulic turbine the combination with an intake adapted todirect flow radiallv inward and impart a whirl to it, of means forvarying said whirl, a draft tube through which the flow passes outwardwith a radial component away from the axis of said whirl, a conduitcontinuously curving in the same direction and leading from said intaketo said draft tube, a turbine runner in said conduit, a dischargepassage receiving the out- How from said draft tube inwardly undercutunder the spreading end and uppercut above the outer wall of said drafttube.

9. In a hydraulic turbine the combination with an intake directed towardthe turbine axis and adapted to impart a whirl to the flow, ofadjustable guide vanes for varying said whirl, an outwardly directedoutlet adapted to discharge a whirling flow with a radial component awayfrom the axis, a conduit leading from said intake to said outletcontinuously curving without suddenchange in curvature, a turbine runnerin said conduit, and a discharge passage receiving the outflow from saidoutlet and inwardlyunderout under the spreading end and uppercut abovethe outer wall of said outlet.

10. In a hydraulic turbine the combination with an intake adapted todirect the water radially inward and impart a whirl to the flow, ofadjustable guide vanes for varying said whirl, an outlet through whichthe flow passes outward with a whirl, a conduit curving in the samedirection and leading from said intake to said outlet, a turbine runnerin said conduit and spaced from said intake so as to leave a curvingtransition space between said intake and said runner, and a dischargepassage receiving the outflow from said outlet and inwardly undercutunder the spreading end and uppercut above the outer wall of saidoutlet.

11. In a hydraulic turbine the combination with a runner, of a drafttube receiving the flow from the runner in a generally axial directionand discharging said flow outwardly awayfrom the turbine axis on allsides, and a volute discharge passage receiving the flow from said drafttube and having a floor below the lower surface of said draft tube.

12. In a hydraulic turbine the combination with a runner, of a drafttube receiving the flow from the runner in a generally axial directionand discharging said flow outwardly away from the turbine axis on allsides, and a discharge passage receiving the flow from said draft tubeand having a floor below the lower surface of said tube and an uppersurface uppercut above the outer wall of said draft tube.

13. In a hydraulic turbine the combination with a draft tube, of adischarge passage receiving the flow from said draft tube havinggradually increasing cross sectional areas adapted for gradualdeceleration of the flow, and a floor below the lower surface of saiddraft tube.

14:. In a hydraulic turbine the combination with a draft tube, of adischarge passage receiving the flow from said draft tube havinggradually increasing cross sectional areas adapted for gradualdeceleration of the flow, and a floor below the lower surface and a roofabove the wall of said draft tube.

15. In a hydraulic turbine the combination with a spreading draft tubehaving a relatively long gradually flaring passage leading from theturbine and a central core extending into said passage for turning theflow outward from its axis, of a collector passag-e receiving the flowfrom the draft tube, a portion of said collector passage having a roofdisposed at a point intermediate of the top and "bottom surfaces of thecollector passage.

16. In a'hydraulic turbine the combination With a spreading draft tubehaving agraduallyfiaring Wall of substantial length, of a central" corereceiving the flow from the. turbinefrunner in a generallyaxialdirection and discharging said flow outwardly away from the turbine axison all sides and a discharge passage receiving "the flow from said draft.tube at a point intermediate its topand bottonasurfaces and asubstantial distance from said bottom surface.

and having inner and outer cooperating spiral Walls.

18. In a hydraulic turbine, thBCOlHblllition with a draft tube,-of acollectorpassage having inner and outer cooperating spiral Walls, saidcollector passage having portions of its roof at different elevations.

19. In a hydraulic turbine, the combination with a draft tube having .acentral core, 'of a collector passage having inner and outer cooperatingspiral Walls, the spiral of Which begins at a point adjacent to the baseof said central core.

20. In a hy'draulicturbine, the combination With -a draft tube havingacentral core,

of a collector passage having inner and outer cooperating spiral Wallsterminating .in a

downstream direction, the spiral of which passage.

LEWIS FERRY IMOODY.

